Separate the 2 pieces, then drive them back to the start!

"A prize winner from the 2001 1st Annual World Puzzle Design Competition, this puzzle was designed by young Dutch phenomenon, Oskar van Deventer, considered one of the world’s brightest creators.
The gear exhibits a unique kind of movement.
Once together in its final form of beauty, this puzzle could very well serve as a desk decoration to satisfy a kind of soothing, intellectual curiosity.
The key word is 'teeth'."

-NOB, Cast designer